The Perfert 338 Lapua Mag Build

[Rum Man]

Sealesniper after reading you first post again in the picture the scope is actually tilted 105 moa . I had to think about your question some .
Actually I dont need the 55 moa base the 200 min. adj base will work .
I have about 325 min.of elevation with that set up witch will put me past the cartridge capability. But it would be fun to try .

Rum Man

 

[FurTaker]

Tagging in

 

[Coyote Shadow Tracker]

Back at it again. We are in the process of sending in a "Sample Cartridge" to JGS to have a customer reamer made for our 338LMAI build. I am going to be using Berger 300 OTMs. Some data books for loads show 3.60" for the coal, but these 300 OTMs a much different )(Longer). Looking at the coal of 3.75 - 3.80". I know to reload and see where the lands start goes by the ogive of the bullet, but I am now making the barrel to the bullet. I did match up a 300gr Sencar loaded to 3.60 with how much the bullet was in the case and then compared the 300 OTM and they have both the same amount base in the case, but 300otm has .225" longer outside.
Is anyone loading the 300OMTs in a 338 LM or AI and with is your COAL? This is a single action so don't have to worry about fitting the cartridge into a mag.

Thanks
Len

 

[Coyote Shadow Tracker]

I think I got it dialed in. I have a bunch of 250 and 300gr Lapua Scena Match factory loaded and I measured the ogives and compared to the Berger 300gn OTMs.. Much longer COAL. I'll have JGS make the reamer to my the neck size and throat to the 300 OTMs. Want to make this chamber really tight. I purchased two Krieger 338 barrels that were the only ones in stock, but don't like to profile, so looking for other ones. I really wanted 1.25 or 1.35 straight 33" 1:9 but was being told to go with the 1:9.35.
Any thoughts on twist for 300 OTMs?

 

[Dragoon300]

I had Bartlien make a 31" .338 5R 1:10.35 to 1:9.35 LH gain twist. I had Manson make a custom reamer to my loaded round, a standard .338 Lapua throated to accept 300 grain Berger OTM's seated @ 3.9375" COAL .010" off the lands. I have used these loads for 5 years now in two different barrels for my Desert Tech SRS-A1. Both the 26" factory barrel throated deeper, and the 31" Bartlien give me 1/4 MOA groups. My magazine length is 4" and functions well.

 

[Coyote Shadow Tracker]

I had Bartlien make a 31" .338 5R 1:10.35 to 1:9.35 LH gain twist. I had Manson make a custom reamer to my loaded round, a standard .338 Lapua throated to accept 300 grain Berger OTM's seated @ 3.9375" COAL .010" off the lands. I have used these loads for 5 years now in two different barrels for my Desert Tech SRS-A1. Both the 26" factory barrel throated deeper, and the 31" Bartlien give me 1/4 MOA groups. My magazine length is 4" and functions well.

Awesome! thanks for your fast response. I was a little concerned on the COAL and pulling the bullet out so far from the case. I am going to have Bartlien make me a blank so I can finish to 31". I talked to Mark at B about the same Gain twist. For now I am going to get a barrel for now an wait on the B.
What is the diameter of your Bartlien and what action you running???

Thanks
Len

 

[Elk Hunter 338]

Here's a pretty standard 338 Lapua for ya!

 

[Coyote Shadow Tracker]

Here's a pretty standard 338 Lapua for ya!
View attachment 286273View attachment 286274View attachment 286275View attachment 286276View attachment 286277

Really a BEAUTIFL Rifle!!!!!!!!!!!!!!!

 

[Dragoon300]

Awesome! thanks for your fast response. I was a little concerned on the COAL and pulling the bullet out so far from the case. I am going to have Bartlien make me a blank so I can finish to 31". I talked to Mark at B about the same Gain twist. For now I am going to get a barrel for now an wait on the B.
What is the diameter of your Bartlien and what action you running???

Thanks
Len

My Desert Tech SRS barrels have a 1.2500" diameter shank 5-1/2" long over the chamber end to clamp on, they step down slightly then have a straight taper from there to the muzzle. Mark worked with me on my barrels, I also had him do a 31" 6.5 mm that I chambered in PRC.

 

[Elk Hunter 338]

you ever get yours figured out @coyoteshadowtracker?

 

[Coyote Shadow Tracker]

you ever get yours figured out @coyoteshadowtracker?

Elk
I wish! I have several other builds going on and was not going to start the 338 until some time in 2022. I went to a shoot at the Arena in GA a month or so ago and got the bug shooting at 2,300 meters. We have bullets, brass, primers, powder and ordering the custom reamer tomorrow. I just bought two barrels, but don't want to use them and have tow more ordered.
Hopefully I'll have the action and stock bought next week.
Will keep you updated.
Thanks
Len

 

[surgeon260]

My single shot 338 Lapua AI is throated for the Berger 300 OTM. My COAL at the lands is 3.925.

 

[C.O. Shooter]

Do you believe you will see a difference from 1-9.35 vs 1-9? Negative!

 

[TXAoudadKlr]

I'd look at Kirby's LRSS for inspiration.

I'd maintain everything about it just only minor changes. I'd have the barrel finish at .880" @ 30" and run a T3 Terminator brake also, I love the super mag A5